/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.beans.factory.wiring;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.beans.factory.BeanCreationException;
import org.springframework.beans.factory.BeanCurrentlyInCreationException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;

/**
 * Convenient base class for bean configurers that can perform Dependency Injection
 * on objects (however they may be created). Typically subclassed by AspectJ aspects.
 *
 * <p>Subclasses may also need a custom metadata resolution strategy, in the
 * {@link BeanWiringInfoResolver} interface. The default implementation looks for
 * a bean with the same name as the fully-qualified class name. (This is the default
 * name of the bean in a Spring XML file if the '{@code id}' attribute is not used.)
 *
 * @author Rob Harrop
 * @author Rod Johnson
 * @author Juergen Hoeller
 * @author Adrian Colyer
 * @see #setBeanWiringInfoResolver
 * @see ClassNameBeanWiringInfoResolver
 * @since 2.0
 */
public class BeanConfigurerSupport implements BeanFactoryAware, InitializingBean, DisposableBean {

    /**
     * Logger available to subclasses.
     */
    protected final Log logger = LogFactory.getLog(getClass());

    @Nullable
    private volatile BeanWiringInfoResolver beanWiringInfoResolver;

    @Nullable
    private volatile ConfigurableListableBeanFactory beanFactory;


    /**
     * Set the {@link BeanWiringInfoResolver} to use.
     * <p>The default behavior is to look for a bean with the same name as the class.
     * As an alternative, consider using annotation-driven bean wiring.
     *
     * @see ClassNameBeanWiringInfoResolver
     * @see org.springframework.beans.factory.annotation.AnnotationBeanWiringInfoResolver
     */
    public void setBeanWiringInfoResolver(BeanWiringInfoResolver beanWiringInfoResolver) {
        Assert.notNull(beanWiringInfoResolver, "BeanWiringInfoResolver must not be null");
        this.beanWiringInfoResolver = beanWiringInfoResolver;
    }

    /**
     * Set the {@link BeanFactory} in which this aspect must configure beans.
     */
    @Override
    public void setBeanFactory(BeanFactory beanFactory) {
        if (!(beanFactory instanceof ConfigurableListableBeanFactory)) {
            throw new IllegalArgumentException(
                    "Bean configurer aspect needs to run in a ConfigurableListableBeanFactory: " + beanFactory);
        }
        this.beanFactory = (ConfigurableListableBeanFactory) beanFactory;
        if (this.beanWiringInfoResolver == null) {
            this.beanWiringInfoResolver = createDefaultBeanWiringInfoResolver();
        }
    }

    /**
     * Create the default BeanWiringInfoResolver to be used if none was
     * specified explicitly.
     * <p>The default implementation builds a {@link ClassNameBeanWiringInfoResolver}.
     *
     * @return the default BeanWiringInfoResolver (never {@code null})
     */
    @Nullable
    protected BeanWiringInfoResolver createDefaultBeanWiringInfoResolver() {
        return new ClassNameBeanWiringInfoResolver();
    }

    /**
     * Check that a {@link BeanFactory} has been set.
     */
    @Override
    public void afterPropertiesSet() {
        Assert.notNull(this.beanFactory, "BeanFactory must be set");
    }

    /**
     * Release references to the {@link BeanFactory} and
     * {@link BeanWiringInfoResolver} when the container is destroyed.
     */
    @Override
    public void destroy() {
        this.beanFactory = null;
        this.beanWiringInfoResolver = null;
    }


    /**
     * Configure the bean instance.
     * <p>Subclasses can override this to provide custom configuration logic.
     * Typically called by an aspect, for all bean instances matched by a pointcut.
     *
     * @param beanInstance the bean instance to configure (must <b>not</b> be {@code null})
     */
    public void configureBean(Object beanInstance) {
        if (this.beanFactory == null) {
            if (logger.isDebugEnabled()) {
                logger.debug("BeanFactory has not been set on " + ClassUtils.getShortName(getClass()) + ": " +
                        "Make sure this configurer runs in a Spring container. Unable to configure bean of type [" +
                        ClassUtils.getDescriptiveType(beanInstance) + "]. Proceeding without injection.");
            }
            return;
        }

        BeanWiringInfoResolver bwiResolver = this.beanWiringInfoResolver;
        Assert.state(bwiResolver != null, "No BeanWiringInfoResolver available");
        BeanWiringInfo bwi = bwiResolver.resolveWiringInfo(beanInstance);
        if (bwi == null) {
            // Skip the bean if no wiring info given.
            return;
        }


        ConfigurableListableBeanFactory beanFactory = this.beanFactory;
        Assert.state(beanFactory != null, "No BeanFactory available");
        try {
            String beanName = bwi.getBeanName();
            if (bwi.indicatesAutowiring() || (bwi.isDefaultBeanName() && beanName != null &&
                    !beanFactory.containsBean(beanName))) {
                // Perform autowiring (also applying standard factory / post-processor callbacks).
                beanFactory.autowireBeanProperties(beanInstance, bwi.getAutowireMode(), bwi.getDependencyCheck());
                beanFactory.initializeBean(beanInstance, (beanName != null ? beanName : ""));
            } else {
                // Perform explicit wiring based on the specified bean definition.
                beanFactory.configureBean(beanInstance, (beanName != null ? beanName : ""));
            }
        } catch (BeanCreationException ex) {
            Throwable rootCause = ex.getMostSpecificCause();
            if (rootCause instanceof BeanCurrentlyInCreationException) {
                BeanCreationException bce = (BeanCreationException) rootCause;
                String bceBeanName = bce.getBeanName();
                if (bceBeanName != null && beanFactory.isCurrentlyInCreation(bceBeanName)) {
                    if (logger.isDebugEnabled()) {
                        logger.debug("Failed to create target bean '" + bce.getBeanName() +
                                "' while configuring object of type [" + beanInstance.getClass().getName() +
                                "] - probably due to a circular reference. This is a common startup situation " +
                                "and usually not fatal. Proceeding without injection. Original exception: " + ex);
                    }
                    return;
                }
            }
            throw ex;
        }
    }

}
